-2 types
-arise in part from lymphocyte colonies in various lymphoid tissues originally populated by cells derived from bone marrow
*B lymphocytes- tranformed into plasma cells, secrete antibodies and indirectly lead to the destruction of foreign material
*T lymphocytes- cell-mediated immunity involving direct destruction of virus-invaded cells and mutant cells through nonphagocytic means

-filter potential pathogens that gain access to lymph
-pathogens exposed to pymphocytes and macrophages that line lymphatic pathways
-spleen, largest lymphoid tissue

thymus and bone marrow

-important roles in processing T and B lymphocytes to prepare them to carry out their specific immune strategies

innate immune system

-encompasses the body's nonspecific immune responses that some into play IMMEDIATELY on exposure to threatening agent
-inherent (build-in) befense mechanisms that nonselectively defend against foreign or abnormal material
-first line of defense against infections agents, chemical irritants, and tissue injury from mechanical trauma and burns
-born with it
-plasme proteins, neutrophils, macrophages (phagocytic specialists) are important
*inflammation
*interferon (family of proteins that nonespecifically defend against virual infection)
*Natural killer cells (special calss of lymphocyte-like sells that spontaneously and nonspecifically lyse and destroy virus-infected host cells and cancer cellsw)
*the complement system (group of inactive plasma proteins thatn, when activated, bring about destruction of foreign cells by attacking plasma mems)

toll-like receptors (TRLs)
(innate immune sys)

-toll-like receptors (TLRs) (type of plasma mem) "eyes of the innate immune sys"
-recognize and with with the telltale pathogen markers
-allows effector cells of innate immune sys to "see" pathogens as distinct from celf-cells
-triggers the pagocyte to engulf and destroy the infectious micro-organism
-induces the phagocytic cell to secrete chemicals (inflammation)
-link innate and adaptive
-foreign particles marked for phagocytic ingestion by being coated with antibodies produced by the B cells of adaptive immune sys.

adaptive immune system

-responces mediated by the B and T lymphocytes
-each B and T can recognize and defend against only ONE particular type of foreign material (ie. 1 type of bacterium)
-"specially trained military personnel"
-chosen lymphocytes multiply, expanding the pool of speicalists that can launch a highly targeted attack against the invader
-ultimate weapon against most pathogens
-system acquires an ability to more efficiently eradicate a particular foe when rechallenged by the same pathogen in the future
-establishing a pool of MEMORY CELLS as a result of an encounter with a given pathogen; subsequent exposure to the same agent means it can more swiftly defent against the invader

inflammation

-refers to innate, nonspecific series of highly interrelated events that are set into motion in response to foreign invasion, tissue damage, or both
-goal is to bring the invaded/injured area phagocytes and plasma proteins that can
1.isolate, destroy, or inactivate the invaders
2. remove debris
3. prepare for subsequent healing and repair
*defense by resident tissue macrophages
*localized vasodilation
*increased capillary permeability
*localized edema
*walling off of the inflamed area
*emigration of leukocytes
*leukocyte proliferation
*marking of bacteria for destruction by opsonins
*leukocytic destruction of bacteria
*mediation of the inflammatory response by phagocyte-secreted chemicals
*tissue repair
ETC. p 416-423

antigen

-a large, complex, unique molecule tha ttriggers a specific immine response against itself when it gains entry into the body
-more complex=greater its antigenicity
-foreign proteins most common antigens b/c of size and structural complexity
-may exist as isolated molecules (bacterial toxins)
-or may be integral part of a multimolecular structure

-naturally occuring
-lymphocyte-like cells
-nonspecifically destroy virus-infected cells and cancer cells by DIRECTLY lysing their membranes upon first exposure
-similer to cytotoxic T cells
-immediate, nonspecific defense against virus-inecvaded cells and cancer cells before the more specific and more abundant cytotoxic T cells

opsonins

-body-produced chemical that links bacteria to macrophages, thereby making the bacteria more susceptible to phagocytosis
-most important are antibodies and one of the activated proteins of the complement system
-

interferon

-a chemical released from virus-invaded calls that provides nonspecific resistance to viral infections by transiently interfering with replication of the same or unrelated viruses in other host cells